The present invention relates to an apparatus for treating water or liquids in general.
As is known, in the households there is an increasingly frequent use of systems for treating potable water that are based on the principle of reverse osmosis.
The systems commonly used are substantially of two types: accumulation systems and direct production systems.
Differently from direct production systems, accumulation systems utilize the pressure of the water mains and produce the treated water drop by drop, i.e. the permeate, which is accumulated in a tank.
In greater detail, after passing through an activated carbon pre-filter in order to remove organic pollutants and chlorine-based compounds, the water to be treated encounters an osmosis membrane that separates the permeate from the waste; the permeate is sent to the tank while the waste is discharged.
In general, a conventional reverse osmosis accumulation apparatus also includes an activated carbon post-filter, followed by a UV ray lamp that has a germicidal action, all installed downstream of the accumulation tank.
In the prior art, accumulation occurs by means of expansion vessels with a capacity comprised between 12 and 24 liters.
Those expansion vessels contain a buffer volume tank of air under pressure that is separated from the chamber that contains the water by means of an elastomeric membrane.
Although they are advantageous in many respects and comply with their original purpose, reverse osmosis filtration systems with conventional accumulation have some critical aspects, which mainly reside in the characteristics of the accumulation tanks.
The causes of those drawbacks are to be attributed first of all to the fact that the useful volume of water that can be contained under pressure in each expansion vessel is comprised generally between one half and one quarter of the total volume of the vessel, depending on the pressure in the water mains and on the preloading.
In addition to this, it should be considered that the expansion vessel requires periodic maintenance in order to check the preloading pressure which, if necessary, must be topped up.
Also, during the delivery of water from the expansion vessel, the pressure in the vessel decreases progressively, causing a relative reduction of the flow-rate of the service.
Another critical aspect is that conventional accumulation osmosis systems require a flow regulator in order to set the flow-rate of the concentrate.
However, the flow-rate of the flow regulator is independent from the operational step, such as while filling the vessel or during dispensing.
Accordingly, the flow-rate at the service is determined exclusively by the pressure reached in the expansion vessel.
In other words, in conventional accumulation tanks the hydraulic pressure of the concentrate is not utilized to increase the flow-rate at the service.
Another drawback resides in that conventional accumulation reverse osmosis systems for home use require unions and pipes for the hydraulic connection of the various components.
However, unions inherently entail hydraulic tightness risks, assembly risks and space occupation.
A further drawback is the presence of the UV ray lamp, which requires an electric power supply, with electrical and fire risks linked thereto.
It should also be noted that the first water that is delivered, which was present in the chamber of the sterilizer, after a holding period of just a few hours, has a temperature of more than 30° C., which is unpleasant for the user, due to the heat radiated by the UV ray lamp.
Also, exposure to UV rays is harmful for the eyes of the operator.
US2010/116724 discloses a water on water valve assembly for use in reverse osmosis water filtering systems.